DC power supplies, also called power supply units (PSUs) are a variety of low voltage electrical conversion devices. Rectifiers convert AC power to DC power. Inverters convert DC to AC. Sometimes the two are used in conjunction with each other, such as when an inverter first converts DC to AC, followed by a transformer which changes the voltage, finally followed by a rectifier, which converts the power back to DC (at a new level).

The two main types of products available from distributors for DC power systems have many of the same uses, but distinctly different properties. Typical switching DC power supplies convert a main's AC power to DC in order to run electronics. There are also linear DC power supplies which are less complex and produce less electromagnetic interference, but are also less efficient.

Here are some questions you should ask when you are ready to purchase DC power supplies:

1. What is the duration of power the DC equipment supplies per recharge?

2. Is the output voltage of the DC power supply stable under various loads?

3. Does the DC power supply equipment provide constant or pulse power?

4. How much power does the DC equipment supply?

Action Steps
The best contacts and resources to help you get it done

Shop multiple DC power supply manufacturers and distributors

Distributors of DC power supplies and DC power supply manufacturers are numerous, so take advantage of that and check for the item you're interested in at multiple sources. You just might save some money.

I recommend: Neeltran Inc. is a fantastic place to start. They cover one of the widest arrays of applications among distributors for DC power systems, including industrial DC power supplies. Lambda Americas also has a wide selection and PHC Enterprise, Inc. is especially good for adapters and small electronics. For CB and ham radio power supplies go to Tripp Lite. Although they do not sell directly to consumers, they do a good job of directing customers to resellers.

Know your application specifications and buy appropriately

It may be obvious that a DC power supply that matches the electrical specifications of your application, but is too big to fit into your electrical equipment, is not the right power supply. And, just as obvious, if the dimensions are right, but the electrical specifications are wrong, that's not the right power supply either. But it is all too easy to forget one or more specs when ordering.

I recommend: Write down the exact specifications you need and, when you've found an appropriate candidate or two from distributors of DC power supplies, verify each of your specs, one by one. Grainger has only a few power supplies available and lists their dimensions, temperature range and voltage, but other units have polarity or come in an array of classifications and capabilities. Some DC power supplies even convert AC mains to multiple low DC voltage outputs.

Repair your DC power supplies

Power supplies can run hot, especially if there are multiple transformers involved. If your equipment fries, don't automatically think replacement. There are repair options.

I recommend: KF Group provides electronics repair quotes via their website. Also, if you need help with industrial-level installation, head to Lee Industrial Contracting.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  When installing power supplies in tight spaces within electronics, make sure to allow for ventilation and add a fan if applicable.